155 



A weaker acid 

 Kiucli hearier. 



C^eneral infe- 

 rences . 



"Zx peri merits. 

 Addition of 

 ■water increns- 

 «t the sijec. 

 •rav. t a cer- 

 tain point. 



znd then dimi' 

 xtisbed it. 



ON THE STRIiNGTH OF ACETIC ACID. 



determined exactlj^ the quantity vequifite to produce 9° of 

 density, and 113 strength of acid, denoted by the quantity 

 of subcarboaate of soda it would saturate. 



Having observed, that acetic acid saturating 250 of car- 

 bonate of soda, and crystallli^ioo; between I0° and 11° R. 

 [54'5'' and 56-7°], marked but 9° on the areometer; while 

 another specimen of the arid, that marked 11*1° was not 

 crystallizabie even at 4° R. [41° F.], and saturated but 

 186*25 of subcarbonate of soda ; I concUided, 



1, That the areometer cannot measure the strength of 

 acetic acid, without some preliminary steps: 



2, That there must be a point discoverable by the areo- 

 meter, at which the effective acid is in such proportion to 

 the water, as to be capable of exerting in a sensible manner 

 one of its physical properties, that was before imperceptible: 



3, That tliis property must be a dilatability greater than 

 that of water : 



4, That this dilatability, apparent when the acid was in 

 a certain propoition to the water with which I was yet un- 

 acquainted, must increase regularly in proportion as the 

 quantity of water in the mixture diminished : 



5, That the areometer would then regularly indicate the 

 effective quantity of acetic acid in a mixture, by adopting 

 an inverse ratio. 



The following experiments confirmed my reasoning. 



I took 110 gr. of the acid No. 1, containing 0-87125 acid 

 and 0*12875 water, and marking 9° by the areometer, arid 

 gradually added 35*941 gr. of distilled water to the 14*l6 

 already in the UOgr. of acid No. 1, in order that the mix- 

 tureshould contain the quantity of 50-101 gr. necessary to 

 produce an acid of the composition of 65-65 acid to 34*35 

 water, being that of an acid marking ,11*1° on the areo- 

 metey. 



When I had added 32*5 gr. of water to the 110 gr. of 

 No. 1, the mixture indicated 11-3° on the areometer, which 

 was the highest point of density of this acetic acid at the 

 temperature of 1-2*5° R. [60*1 F.] Its composition then was 

 0-6725614 acid, 0-3274386 water. 



On continuing to add water 1 brought the mixture down 

 to 9" of the areometer, which was the density of the original 



acid 



